In a permanent magnet generator, the magnetic field of rotor is produced by permanent magnets.
Permanent magnet generators do not require DC supply for the excitation circuit. They do not contact brushes and slip rings. In permanent magnet alternators, speed is directly proportional to voltage of the alternator.
Synchronous generators form the majority source of commercial electrical energy generation. They are used to convert mechanical power output of gas turbines, steam turbines, reciprocating engines, wind turbines, hydro turbines into electrical power for the grid. They are known as synchronous generators as the frequency is directly proportional to the number of permanent magnet stator poles and the rpm.
PMSG for use in Wind Turbines
Of all the generators that are used in wind turbines the PMSGs have maximum merits for the following features:
o Small Dimension
o Functional without DC supply
o Works at low speed
o Works without gearbox
Permanent magnet synchronous generators make a solution as a variable-speed generator.
PMSG are suitable for use in wind turbines as they are stable and secure during normal operation, have small overall dimensions as compared to wound rotor synchronous generators (WRSGs) and do not require an additional DC supply for excitation circuit or winding. With a multi-pole synchronous generator it can operate at low speeds and in absence of gearbox.
The Permanent Magnet Generator supplies more power than others for starting motor functions. The generator performs to sustain main field excitation for coordination and short circuit fault discrimination, and so provides greater immunity from loads of non-linear format.
In application, the PMG alternator features as a brushless exciter for first load response. The power control devices such as the full wave bridge, solid state, three-phase are designed for the PMG excitation. The process of over-excitation protection continually performs monitoring of the excitation level. And if the level reaches more than the preset level, the regulator shuts down after few seconds.
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With the replacement of mechanical transmission with electric motors, the needed amount of power is provided. This lowers fuel consumption by correct synchronization of the generator set power with the electric driven motors.
The most successful method is provided by a permanent magnet generator (PMG). The engine powers the generator which then powers the electric motors.
PMGL Alternators as Eco-Friendly Power on Roads
The PMG generators charge the battery with a battery system. A major advantage of this is that it the causes the combustion engine to turn off when the vehicle stops which reduces
emissions and fuel consumption.
Series hybrids, also known as the Range Extended Electric Vehicles (REEV) are fitted with the pm generators that function to recharge the battery when needed, for instance in case of a long drive, and also function as engine starters when turned with the combustion engine. In the series-hybrid systems, a vehicle is driven by the use of
electric motors for which the pm generator set supplies the required electric power.
India is on the path of fast economic growth. The most important factor involved in any growth story is the availability of uninterrupted power at a reasonable cost. Looking at the present scenario the picture does not seem to be very glossy. There being a considerable gap between the demand and supply position particularly during peak hours, long power cuts have become a norm rather than exceptions.
In the above backdrop, there is an urgent need to fully exploit and harness renewable energy resources and help the economy by providing clean and adequate power. Wind power is one such sphere where a lot can be done.
We on our part are manufacturing among other products permanent magnet generators for wind turbines that can be used for various applications. As our country has a coastline measuring over 7000 KMs, there is a vast scope for harnessing wind energy for generating power at a reasonable rate. We welcome inquiries for wind customized permanent magnet generators to meet the challenge for providing, clean and continuous power to our ever-growing economy.
Donauer Al Badi Gulf is a joint venture between Germany’s Donauer and NAS International. Their latest technology is based on a hybrid solution for power generation. A state of art solution including solar based panels is developed for commercial use in Middle Eastern countries.
Due to shortage of electricity during summers, the dependency on diesel generators increases. The latest technology is a combination of diesel generators and solar designs to produce electricity from the combination of the two processes. This way a saving of 30-40% generation cost will be seen. The solar process which is cheaper to produce electricity will produce electricity first. An artificial intelligence sensor will detect the deficit and automatically that demand will be fulfilled by the diesel generator.
Remote areas which are not connected to the power grid and which rely on diesel generators can also be benefited from this technology. Also, such projects, if developed on a larger scale can produce employment for many in the villages. Compared to almost 5 years taken by diesel generator setup, solar projects can be completed in less than a year. Such innovative ideas help save the natural fuel of the nature which are presently used to generate electricity.
Here are some new technologies developed by big brand names in the field of marine energy development.
Albatern: WaveNET technology
Based on the technology of modules and associated nodes, this project has been granted 617,000 pounds under the WATERS2 scheme. With a development and testing phase in the period of late 2012 to late 2013, this project is capable of becoming a 10MW energy proposition.
AWS Ocean Energy: AWS-III Wave Energy Converter (WEC)
Awarded with a grant of 3.9 million pounds, this project has a rated power output of 2.5MW. A full prototype plan is planned in 2014. The technology involved is a multi cell array of flexible membranes.
Aimed to reduce the complexity of operations, the CoRMaT can deliver the tidal power without needing big and heavy supporting structures.
Oceanflow Energy: Oceanflow’s ‘Evopod’ tidal technology
The company’s strategy is to build an operating experience with its 35 kW mono turbine and 70 kW twin turbine Evopod units. The technology involves a semi submerged floating body that is tethered to the seabed by a multi-line spread mooring system.
Scotrenewables Tidal Power: SRTT
This technology features two contra rotating rotors that excite that extract the kinetic energy of the tidal flow, which is converted to electricity though a power take-off system.Company’s WATERS project will involve the design, construction and installation at EMEC of a commercial demonstrator SRTT rated up to 2 MW.
The UK has become a world leader in development of marine energy projects. The UK will be home to the first multi MW commercial array project. Tidal energy has been given due acknowledgment and is considered as a significant contributor to the energy demand.Tidal power plays an important role in reducing the dependability on other sources like imported fuels.
The marine energy industry has been in a state of technological developments recently. The efforts of many companies are being rewarded by various Government organizations which provide financial aid to boost research so that the industry keeps developing forward.
The most recent announcement was made by the Scottish Government which said that a funding of 7.9 million pounds would be given to boost the developments of five marine energy developers. The marine energy market is developing rapidly and keeping that in mind The WATERS (Water and Tidal Research Development and Demonstration Support) program has been released. The Scottish energy market has a potential to benefit their economy by an amount of 4 billion pounds with wave technology.
The output voltage of a permanent magnet alternator depends on the shaft rpm and the load. The higher the rpm, the higher is the voltage. The higher the load for a given rpm, the lower is the voltage.
Connection to Current and RPM o Load
The current (“amperage”) of a dc generator at any rpm is not governed by its rpm but only by the load put on it. This means that if you run a generator with no load, the current stays at zero no matter how high the rpm is. Only the generator terminal voltage goes up in such case.
Frequency is related to the rpm and the number of poles the generator has. The more the number of poles, the higher is the frequency at a given rpm.
In marine environments where the sources of electricity are scarce, batteries are the only viable option and due to high wind speed at sea, these wind turbine battery charging options become a very profitable and convenient source. The overall cost of electricity is reduced. Also with battery usage the overall capacity of the site is doubled. The wind turbine produces the electricity and the battery stores the extra electricity.
The initial setup is simple. The connection diagram is shown below.
Since the generator is a permanent magnet one, the efficiency obtained in converting mechanical energy to electrical energy is maximum. It is more than 90% efficient, which means that more than 90% of the applied mechanical force by the wind is converted into electricity. Compared to 70% provided by traditional generators the amount of wastage is minimal. With such high efficiencies in permanent magnet generators, the fuel savings are more, the batteries last longer and overall cost of using electricity is decreased.
The market for small wind turbines is providing added electrification needed in remote areas. Many parts of the world are still running on electricity from batteries rather than electrical grids laid by national power corporations. Telecom companies who have to provide uninterrupted signals in remote areas rely on batteries and generators to get electricity. Another area that uses battery back up is Marine operations. Off grid wind turbines are proving to be increasingly valuble in these situations.
Wind speed is not always constant and it is usually highest during the night hours when people are not using much electricity. Storage of this night-time electricity can charge the battery and become an important method to utilize this electricity that could be lost.
Installing a small wind permanent magnet generator at remote sites can provide battery charging at a much lower cost than diesel generation or charging stations. Since there are no recurring costs with wind energy, the payback period of the initial setup cost is minimal.